Low friction and low traction lubricant compositions useful in dry clutch motorcycles

ABSTRACT

Low friction and low traction lubricant compositions that are particularly useful in dry clutch motorcycles and processes for making same. In some embodiments, a lubricant composition can include: an oil base stock consisting essentially of at least one monoester, wherein a concentration of the at least one monoester is about 70.00 to about 90.00 mass %; about 0.20 to about 1.50 mass % of at least one antiwear additive; about 0.10 to about 1.00 mass % of at least one friction modifier; about 1.00 to about 4.00 mass % of at least one dispersant; less than about 0.5 mass % of phosphorus; less than about 0.1 mass % of sulfur; and less than about 0.5 mass % of ash. The lubricant composition can have a traction coefficient that is greater than about 0.010 and less than about 0.023 and an average friction coefficient that is greater than about 0.01 and about less than about 0.10.

FIELD OF THE INVENTION

Embodiments of the present invention generally relate to lubricant compositions and processes for making same. More particularly, such embodiments relate to low friction and low traction lubricant compositions that can be used to lubricate both the engine and the gearbox in, e.g., a dry clutch motorcycle, and processes for making same.

BACKGROUND OF THE INVENTION

In dry clutch motorcycles, the engine lubricant not only lubricates the engine but also the gearbox. Conventional engine lubricants are typically designed to reduce the friction between the moving parts in the engine. This “friction” is the force that resists the relative motion of solid surfaces sliding against each other under the boundary lubrication condition. For a dry clutch motorcycle to achieve higher power efficiency and better fuel economy, the engine lubricant needs to provide for low traction in the gearbox as well as low friction in the engine. This “traction” is the frictional force that is transmitted across an interface between two bodies through an intervening fluid film under the elastohydrodynamic lubrication (EHL) condition. Unfortunately, conventional motorcycle lubricants typically fail to provide both low friction for the engine and low traction for the gearbox.

Conventional engine lubricants used in dry clutch motorcycles contain, among other things, an oil base stock, at least one metal-containing antiwear additive to reduce friction between moving parts, at least one metal-containing detergent to help maintain engine cleanliness, and at least one dispersant to suspend contaminants in the oil. The oil base stock is typically made of mineral oil or a synthetic oil such as polyalphaolefin. Phosphorus- and sulfur-containing compounds such as zinc dialkyldithiophosphates are commonly used as the antiwear additive. Examples of detergents that are typically used in the engine lubricant include calcium sulfonates, calcium salicylates, and magnesium sulfonates. Over time such metal-containing antiwear additives and detergents can lead to the formation of an ashy residue in the engine lubricant.

The sulfur, phosphorus, and ash present in conventional dry clutch motorcycle lubricants can adversely affect engine post-treatment devices and the catalyst used in such devices. For example, the presence of ash can impact particulate filters that could potentially be used in motorcycles to meet emission requirements. The ash accumulated in the particulate filters can increase engine back pressure, leading to poorer fuel economy.

A need therefore exists for dry clutch motorcycle engine lubricants that provide for less friction between moving parts in the engine and less traction between moving parts in the gearbox. Engine lubricants that contain less sulfur, phosphorus, and ash are also desired.

SUMMARY

Low friction and low traction lubricant compositions and process for making same are provided. Such lubricant compositions can be employed to lubricate both the engine and the gearbox in, e.g., a dry clutch motorcycle

In one or more embodiments, a lubricant composition can include: an oil base stock consisting essentially of at least one monoester, wherein a concentration of the at least one monoester is about 70.00 mass % to about 90.00 mass %; about 0.20 mass % to about 1.50 mass % of at least one antiwear additive; about 0.10 mass % to about 1.00 mass % of at least one friction modifier; about 1.00 mass % to about 4.00 mass % of at least one dispersant; less than about 0.5 mass % of phosphorus; less than about 0.1 mass % of sulfur; and less than about 0.5 mass % of ash, wherein all mass percentages are based on a total mass of the lubricant composition. The lubricant composition can have a first traction coefficient that is greater than about 0.010 and less than about 0.023, as measured by the Traction Coefficient Test at a temperature of about 140° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%. The lubricant composition can also have an average friction coefficient that is greater than about 0.01 and about less than about 0.10, as measured by the Friction Coefficient Test at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%.

In one or more embodiments, a lubricant composition can include: an oil base stock comprising at least one monoester and at least one polyalphaolefin, wherein a concentration of the at least one monoester is about 50.00 mass % to about 90.00 mass % and a concentration of the at least one polyalphaolefin is about 10.00 mass % to about 20.00 mass %; about 0.20 mass % to about 2.50 mass % of at least one antiwear additive; about 1.50 mass % to about 2.50 mass % of at least one friction modifier; and about 1.00 mass % to about 4.00 mass % of at least one dispersant, wherein all mass percentages are based on a total mass of the lubricant composition. The lubricant composition can have a first traction coefficient that is greater than about 0.010 and less than about 0.023, as measured by the Traction Coefficient Test at a temperature of about 140° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%. Moreover, the lubricant composition can have an average friction coefficient that is greater than about 0.01 and about less than about 0.10, as measured by the Friction Coefficient Test at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%.

In one or more embodiments, a lubricant composition can include: an oil base stock comprising at least one monoester and at least one polyalphaolefin, wherein a concentration of the at least one monoester is about 15.00 mass % to about 30.00 mass % and a concentration of the at least one polyalphaolefin is about 30.00 mass % to about 55.00 mass %; about 0.20 mass % to about 2.50 mass % of at least one antiwear additive; about 1.50 mass % to about 2.50 mass % of at least one friction modifier; and about 1.00 mass % to about 4.00 mass % of at least one dispersant, wherein all mass percentages are based on a total mass of the lubricant composition. The lubricant composition can have a first traction coefficient that is greater than about 0.010 and less than about 0.023, as measured by the Traction Coefficient Test at a temperature of about 140° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%. The lubricant composition can further have an average friction coefficient that is greater than about 0.01 and about less than about 0.10, as measured by the Friction Coefficient Test at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended figure. It is to be noted, however, that the appended drawing illustrates only typical embodiments of this invention and is therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1 is a bar graph depicting the average friction coefficient for various lubricant compositions, according to one or more embodiments provided herein.

FIG. 2 is a bar graph depicting the traction coefficient at different temperatures for various lubricant compositions, according to one or more embodiments provided herein.

DETAILED DESCRIPTION

It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, and/or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the Figures. Moreover, the exemplary embodiments presented below can be combined in any combination of ways, i.e., any element from one exemplary embodiment can be used in any other exemplary embodiment, without departing from the scope of the disclosure.

Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities can refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function.

In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” The phrase “consisting essentially of” means that the described/claimed composition does not include any other components that will materially alter its properties by any more than 5% of that property, and in any case does not include any other component to a level greater than 3 mass %.

The term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein.

The indefinite articles “a” and “an” refer to both singular forms (i.e., “one”) and plural referents (i.e., one or more) unless the context clearly dictates otherwise. Thus, embodiments using “an antioxidant” include embodiments where one, two, or more antioxidants are used, unless specified to the contrary or the context clearly indicates that only one antioxidant is used.

The term “mass %” means percentage by mass such as percentage by weight, “vol %” means percentage by volume, “mol %” means percentage by mole, “ppm” means parts per million, and “ppm wt” and “wppm” are used interchangeably and mean parts per million on a weight basis. All concentrations herein, unless otherwise stated, are expressed on the basis of the total amount of the composition in question.

The terms “polymer” and “oligomer” are used interchangeably, referring to any two or more of the same or different repeating units/mer units or units. The term “homopolymer” refers to a polymer having units that are the same. The term “copolymer” refers to a polymer having two or more units that are different from each other and includes terpolymers and the like. The term “terpolymer” refers to a polymer having three units that are different from each other. The term “different” as it refers to units indicates that the units differ from each other by at least one atom or are different isomerically. Likewise, the definition of polymer, as used herein, includes homopolymers, copolymers, and the like.

The term “oil base stock” refers to a base fluid that can be used in a lubricant composition. The terms “base oil”, “oil base stock”, and “basestock” are used interchangeably.

The term “alphaolefin” refers to any linear or branched compound of carbon and hydrogen having at least one double bond between the α and β carbon atoms. For purposes of this specification and the claims appended thereto, when a polymer or copolymer is referred to as including an alpha-olefin, e.g., polyalphaolefin, the alpha-olefin present in such polymer or copolymer is the polymerized form of the alpha-olefin. The term “friction coefficient” refers to the ratio of the frictional force and the normal force under boundary lubrication regime. The term “traction coefficient” refers to the friction coefficient under full-film elastohydrodynamic lubrication (EHL) regime. These regimes are defined in the Stribeck curve.

Nomenclature of elements and groups thereof used herein are pursuant to the Periodic Table used by the International Union of Pure and Applied Chemistry after 1988. An example of the Periodic Table is shown in the inner page of the front cover of Advanced Inorganic Chemistry, 6th Edition, by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).

A detailed description will now be provided. Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims. Each of the inventions will now be described in greater detail below, including specific embodiments, versions and examples, but the inventions are not limited to these embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the inventions, when the information in this disclosure is combined with publicly available information and technology.

Lubricant Composition

An improved lubricant composition is disclosed that can include an oil base stock containing at least one monoester present in an amount of about 15.00 to about 90.00 mass %, preferably about 50.00 to about 90.00 mass %, and more preferably about 70.00 to about 90.00 mass %, based on a total mass of the lubricant composition. Surprisingly, a lubricant composition having such a large concentration of monoester can have a relatively low average friction coefficient of about 0.01 to about 0.10, more preferably about 0.01 to about 0.09, and most preferably about 0.01 to about 0.05, as measured by the Friction Coefficient Test (see the Examples) at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%. The lubricant composition also can have the following surprisingly low traction coefficients: about 0.010 to about 0.023, more preferably about 0.010 to about 0.020, and most preferably about 0.010 to about 0.018 at 140° C.; about 0.010 to about 0.024, more preferably about 0.010 to about 0.020, and most preferably about 0.010 to about 0.018 at 120° C.; about 0.010 to about 0.032, more preferably about 0.010 to about 0.029, and most preferably about 0.010 to about 0.027 at 60° C. The traction coefficients are measured by the Traction Coefficient Test (see the Examples) at a pressure of about 1.25 GPa and a slide to roll ratio of about 100.

In one or more embodiments, the lubricant composition is a sulfur-free, ashless, low phosphorus-containing lubricant composition. In addition to containing at least one monoester, this lubricant composition also can include at least one ashless antiwear additive, at least one ashless detergent, at least one antioxidant, at least one friction modifier, and at least one viscosity index improver. The term “sulfur-free” means that the lubricant composition has less than about 0.05 mass %, preferably less than about 0.03 mass %, and more preferably less than about 0.01 mass %, of sulfur. The term “ashless” means that the lubricant composition has less than about 0.05 mass %, preferably less than about 0.03 mass %, and more preferably less than about 0.01 mass %, of metal material. The term “low phosphorus-containing” means that the lubricant composition less than about 0.05 mass %, preferably less than about 0.03 mass %, and more preferably less than about 0.01 mass %, of phosphorus. All of the foregoing mass percentages are based on the total mass of the lubricant composition.

Since the lubricant composition unexpectedly exhibits relatively low friction and low traction coefficients, the lubricant composition can be used to provide for both low friction in an engine and low traction in a gearbox of a dry clutch motorcycle. As a result of the combined low friction in the engine and low traction in the gearbox, better fuel economy can be achieved using this lubricant composition. Also, the use of this lubricant composition can improve the power efficiency of the motorcycle, allowing the engine to run at lower rotations per minute in relation to the speed of the motorcycle.

In embodiments in which the lubricant composition is sulfur-free, ashless, and contains little phosphorus, the lubricant composition can be used as an engine oil to minimize the adverse effects the oil could otherwise have on post-treatment devices such as particulate filters and the catalysts associated therewith. Accordingly, the longevity of post-treatment devices can be improved by using the lubricant composition disclosed herein.

The lubricant composition can be made by mixing together the various components disclosed above while heating the components using any method known in the art. For example, the various components could be added to a vessel maintained at a temperature of about 60° C. to about 90° C., preferably about 70° C. to about 85° C., followed by mixing the components together with a stirrer at the same temperature.

Oil Base Stock

In one or more embodiments, the oil base stock can consist essentially of at least one monoester. The monoester can be obtained by reacting one Guerbet alcohol, which may or may not be prepared using the Guerbet reaction,such as 2-octyldodecanol, 2-hexyldecanol, and 2-ethylhexanol, or one branched alcohol such as iso-dodecanol, iso-tridecanol, or iso-tetradecanol, with one Guerbet acid, which may or may not be prepared using the Guerbet reaction, such as 2-octyldodecanoic acid, 2-hexyldecanoic acid, and 2-ethylhexanoic acid, or one linear acid such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic (pelargonic) acid, decanoic acid, dodecanoic (lauric) acid, tetradecanoic acid, and hexadecanoic (palmitic) acid, or one branched acid such as iso-hexanoic acid, iso-heptanoic acid, iso-octanoic acid, iso-nonanoic acid, iso-decanoic acid, iso-undecanoic acid, iso-dodecanoic (lauric) acid, iso-tridecanoic acid, iso-tetradecanoic acid, iso-pentadecanoic acid, and iso-hexadecanoic acid. These acids may also include 3,5,5-trimethyl hexanoic acid and neo-decanoic acid.

Preferably, the monoester is derived from 2-octyldodecanol, 2-hexyldecanol, 2-ethylhexanol, iso-dodecanoil, iso-tridecanol, or iso-tetradecanol with 2-octyldodecanoic acid, 2-hexyldecanoic acid, 2-ethylhexanoic acid, heptanoic acid, octanoic acid, nonanoic (pelargonic) acid, decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic (palmitic) acid, 3,5,5-trimethyl hexanoic acid, neo-decanoic acid, iso-undecanoic acid, iso-dodecanoic acid, iso-tridecanoic acid, and iso-tetradecanoic acid.

Examples of specific monoesters useful in the oil base stock include 2-octyldodecylheptanoate, 2-octyldodecyloctanoate, 2-octyldodecylpelargonate, 2-octyldodecyl 2-ethylhexanoate, 2-octyldodecyl 3,5,5-trimethylhexanoate, 2-octyldodecyl neodecanoate, 2-hexyldecyl 2-hexyldecanoate, 2-hexyldecyl dodecanoate, 2-hexyldecyl iso-dodecanoate, 2-hexyldecyl iso-tridecanoate, 2-hexyldecyl iso-tetradecanoate, 2-hexyldecyl 2-hexyldecanoate, iso-tridecyl 2-hexyldecanoate, iso-tetradecyl 2-hexyldecanoate, 2-ethyhexyl dodecanoate (laurate), 2-ethylhexyl hexyldecanoate (palmitate) and any combination thereof. Preferred monoesters are 2-otyldecylpelargonate, 2-ethylhexylaurate, 2-etyhlhexylpalmitate, and any combination thereof.

In alternative embodiments, the monoester can be combined with other synthetic oils such as polyalphaolefin (PAO). The concentration of the PAO in the lubricant formulation can range from about 0 mass % to about 55.00 mass %, preferably about 10.00 mass % to about 20.00 mass %, and more preferably from about 10.00 mass % to about 15.00 mass %, based on the total mass of the lubricant composition. The PAO can include one or more Group IV base oils, as defined by the American Petroleum Institute (API Publication 1509; www.API.org). Group IV base oils are synthetic polymerized olefins.

The number average molecular weight of PAOs, which are known materials and generally available on a major commercial scale from suppliers such as ExxonMobil Chemical Company, Chevron Phillips Chemical Company, BP, and others, can vary from about 250 to about 3,000. PAOs can be made in viscosities up to about 150 cSt (100° C.). The PAOs are typically comprised of relatively low molecular weight polymers or oligomers of alphaolefins, including C₂ to about C₃₂ alphaolefins with the C₈ to about C₁₆ alphaolefins, such as 1-hexene, 1-octene, 1-decene, 1-dodecene and the like, being preferred. Preferred PAOs are poly-1-hexene, poly-1-octene, poly-1-decene and poly-1-dodecene and mixtures thereof, and mixed olefin-derived polyolefins. However, the dimers of higher olefins in the range of C₁₄ to C₁₈ can be used to provide low viscosity base stocks of acceptably low volatility. Depending on the viscosity grade and the starting oligomer, the PAOs can be predominantly trimers and tetramers of the starting olefins, with minor amounts of the higher oligomers, having a viscosity range of 1.5 to 12 cSt. PAO fluids of particular use can have viscosities of, e.g., 3.0 cSt, 3.4 cSt, and/or 3.6 cSt. Bi-modal mixtures of PAO fluids having a viscosity range of 1.5 to 150 cSt also can be used if desired.

PAOs also can be conveniently made by the polymerization of an alphaolefin in the presence of a polymerization catalyst such as a Lewis acid catalyst, e.g, BF₃ or AlCl₃, or a Friedel-Crafts catalyst, e.g., aluminum trichloride, boron trifluoride or complexes of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, and carboxylic acids or esters such as ethyl acetate or ethyl propionate. Suitable methods for making PAOs are disclosed in U.S. Pat. Nos. 4,149,178 and 3,382,291, the relevant portions thereof being incorporated by reference herein in their entirety. Other descriptions of PAO synthesis can be found in the following U.S. Pat. Nos.: 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of C₁₄ to C₁₈ olefins are described in U.S. Pat. No. 4,218,330.

Alternatively or additionally, the catalyst system can be or can include one or more non-metallocene Ziegler-Natta catalysts. Alternatively or additionally, the catalyst system can include a metal oxide supported on an inert material, e.g., chromium oxide supported on silica. Such catalyst systems and uses thereof in the process for making PAOs are disclosed in the following U.S. Pat. Nos. 4,827,073; 4,827,064; 4,967,032; 4,926,004; and 4,914,254.

The catalyst system can alternatively or additionally include one or more metallocene catalysts. Metallocene-catalyzed PAO (mPAO) can be a homopolymer made from a single alphaolefin feed or can be a copolymer made from two or more different alphaolefins, each by employing a suitable metallocene catalyst system. Suitable metallocene catalysts can be or can include one or more simple metallocenes, substituted metallocenes, or bridged metallocene catalysts activated or promoted by, for instance, methylaluminoxane (MAO) or a non-coordinating anion, such as N,N-dimethylanilinium tetrakis(perfluorophenyl)borate or other equivalent non-coordinating anions. mPAO and methods for producing mPAO employing metallocene catalysis are described in WO 2007/011832 and U.S. patent application 2009/0036725.

Homopolymer mPAO compositions can be made from single alphaolefins chosen from alphaolefins in the C₂ to C₃₀ range, preferably C₂ to C₁₆, most preferably C₃ to C₁₄ or C₃ to C₁₂. The homopolymers can be isotactic, atactic, syndiotactic, or of any other appropriate tacticity. The tacticity can be tailored by the choices of polymerization catalyst, polymerization reaction conditions, hydrogenation conditions, or combinations thereof.

Copolymer mPAO compositions can be made from at least two alphaolefins of C₂ to C₃₀ range, and typically have monomers randomly distributed in the finished copolymers. It is preferred that the average carbon number is at least 4.1. Advantageously, ethylene and propylene, if present in the feed, can be present in the amount of less than 50 mass % individually or preferably less than 50 mass % combined. The copolymers can be isotactic, atactic, syndiotactic or of any other appropriate tacticity.

Copolymer mPAO compositions can also be made from mixed feed linear alpha olefins (LAOs) having from two to 26 different linear alphaolefins selected from C₂ to C₃₀ linear alphaolefins. Such mixed feed LAO can be obtained from an ethylene growth process using an aluminum catalyst or a metallocene catalyst. The growth olefins can be mostly C₆ to C₁₈ LAO. LAOs from other processes can also be used.

Useful alphaolefins can be obtained from a conventional LAO production facility, from a refinery, from a chemical plant, and even from Fischer-Tropsch synthesis processes (as reported in U.S. Pat. No. 5,382,739). Alphaolefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, other C₂ to C₁₆ alphaolefins, C₁₆₊ alphaolefins, LAOs, and the like. For example, when used alone, C₂ to C₁₆ alphaolefins, more preferably linear alphaolefins, are suitable to make homopolymers. Other combinations of alphaolefin plus LAO, such as for example, C₄ and C₁₄-LAO, C₆- and C₁₆-LAO, C₈-, C₁₀-, C₁₂-LAO, or C₈- and C₁₄-LAO, C₆-, C₁₀-, C₁₄-LAO, C₄, and C₁₂-LAO, etc., are suitable to make copolymers.

A feed comprising a mixture of LAOs selected from C₂ to C₃₀ LAOs or a single LAO selected from C₂ to C₁₆ LAO, can be contacted with an activated metallocene catalyst under oligomerization conditions to provide a liquid product suitable for use as a component in adhesive formulations. Copolymer compositions made from two or more alphaolefins of C₂ to C₃₀ range, with monomers randomly incorporated into the copolymer, can also be used as a component in adhesive formulations. Other suitable PAOs are described in, for example, U.S. Patent Application No. 2013/0005633.

Antiwear Additive

The lubricant composition can also include an antiwear additive to reduce wear between moving parts. The concentration of the antiwear additive in the lubricant concentration can range from 0 mass % to about 3.00 mass %, more preferably from about 0.20 mass % to about 2.50 mass %, based on the total weight of the lubricant composition.

In one or more embodiments, an ashless antiwear additive can be used in the lubrication composition. The ashless antiwear additive can be or can include an amine phosphate, an over-neutralized amine phosphate, or combinations thereof. In this instance, the amount of antiwear additive present in the lubricant composition can range from about 0 mass % to about 1.00 mass %, more preferably from about 0.20 mass % to about 0.50 mass %, based on the total weight of the lubricant composition.

The amine phosphate can be prepared by reacting an amine compound or a polyamine compound with a phosphoric acid. Suitable amines are disclosed in U.S. Pat. No. 4,234,435, the relevant portions thereof being incorporated by reference herein. An “over-neutralized” amine phosphate is preferred, meaning that a more than sufficient amount of amine is added to neutralize an acid phosphate, and this neutralization can be done with one or more amines.

The phosphorus compounds disclosed herein can be prepared by commonly known reactions. For example, they can be prepared by the reaction of an alcohol or a phenol with phosphorus trichloride or by a transesterification reaction. C6 to C12 alcohols and alkyl phenols can be reacted with phosphorus pentoxide to provide a mixture of an alkyl or aryl phosphoric acid and a dialkyl or diaryl phosphoric acid. Alkyl phosphates can also be prepared by the oxidation of the corresponding phosphites. In any case, the reaction can be conducted with moderate heating. Moreover, various phosphorus esters can be prepared by reaction using other phosphorus esters as starting materials. Thus, medium chain (C6 to C22) phosphorus esters can be prepared by reaction of dimethylphosphite with a mixture of medium-chain alcohols by means of a thermal transesterification or an acid- or base-catalyzed transesterification; see for example U.S. Pat. No. 4,652,416. Such materials are also commercially available: for instance, triphenyl phosphite is available from Albright and Wilson as Duraphos TPP™; di-n-butyl hydrogen phosphite is available from Albright and Wilson as Duraphos DBHP™; and triphenylthiophosphate is available from BASF as Irgalube TPPT™.

An alkyl or aryl phosphoric acid and a dialkyl or diaryl phosphoric acid, or their mixtures, can be neutralized by one or more amines. Amines that can form amine salts with such phosphoric acids include, for example, mono-substituted amines, di-substituted amines and tri-substituted amines. Examples of mono-substituted amines include butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, laurylamine, stearylamine, oleylamine and benzylamine. Examples of di-substituted amines include dibutylamine, dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, dilaurylamine, ditridecylamine, distearylamine, dioleylamine, dibenzylamine, stearyl monoethanolamine, decyl monoethanolamine, hexyl monopropanolamine, benzyl monoethanolamine, phenyl monoethanolamine, and tolyl monopropanolamine. Examples of tri-substituted amines include tributylamine, tripentylamine, trihexylamine, tricyclohexylamine, trioctylamine, trilaurylamine, tristearylamine, trioleylamine, tribenzylamine, dioleyl monoethanolamine, dilauryl monopropanolamine, dioctyl monoethanolamine, dihexyl monopropanolamine, dibutyl monopropanolamine, oleyl diethanolamine, stearyl dipropanolamine, lauryl diethanolamine, octyl dipropanolamine, butyl diethanolamine, benzyl diethanolamine, phenyl diethanolamine, tolyl dipropanolamine, xylyl diethanolamine, triethanolamine, and tripropanolamine.

Polyamines that can form salts with the phosphoric acids provided herein include, for example, alkoxylated diamines, fatty polyamine diamines, alkylenepolyamines, hydroxy containing polyamines, condensed polyamines arylpolyamines, and heterocyclic polyamines. Examples of fatty diamines include mono- or dialkyl, symmetrical or asymmetrical ethylene diamines, propane diamines (1,2, or 1,3), and polyamine analogs of the above. Suitable commercial fatty polyamines are Duomeen C. (N-coco-1,3-diaminopropane), Duomeen S (N-soya-1,3-diaminopropane), Duomeen T (N-tallow-1,3-diaminopropane), and Duomeen O (N-oleyl-1,3-diaminopropane). “Duomeens” are commercially available from Armak Chemical Co. of Chicago, Ill.

Examples of alkylenepolyamines include methylenepolyamines, ethylenepolyamines, butylenepolyamines, propylenepolyamines, pentylenepolyamines, etc. The higher homologs and related heterocyclic amines such as piperazines and N-amino alkyl-substituted piperazines are also included. Specific examples of such polyamines are ethylenediamine, triethylenetetramine, tris-(2-aminoethyl)amine, propylenediamine, trimethylenediamine, tripropylenetetramine, tetraethylenepentamine, hexaethyleneheptamine, pentaethylenehexamine, etc. Higher homologs obtained by condensing two or more of the above-noted alkyleneamines are similarly useful as are mixtures of two or more of the aforedescribed polyamines. Ethylenepolyamine are described in detail under the heading Ethylene Amines in Kirk Othmer's “Encyclopedia of Chemical Technology”, 2d Edition, Vol. 7, pages 22-37, Interscience Publishers, New York (1965). Ethylenepolyamines are often a complex mixture of polyalkylenepolyamines, including cyclic condensation products.

Other useful types of polyamine mixtures are those resulting from stripping of mixures of the above-described polyamines to leave, as residue, what is often termed “polyamine bottoms”. In general, alkylenepolyamine bottoms can be characterized as having less than 2 mass %, usually less than 1 mass %, of material boiling below about 200° C. A typical sample of such ethylene polyamine bottoms obtained from the Dow Chemical Company of is designated “E-100”. These alkylenepolyamine bottoms include cyclic condensation products such as piperazine and higher analogs of diethylenetriamine, triethylenetetramine, and the like. The alkylenepolyamine bottoms can be reacted solely with the acylating agent or they can be used with other amines, polyamines, or mixtures thereof. Another useful polyamine is a condensation reaction between at least one hydroxy compound with at least one polyamine reactant containing at least one primary or secondary amino group. The hydroxy compounds are preferably polyhydric amines. Polyhydric amines can include any of the above-described monoamines reacted with an alkylene oxide (e.g., ethylene oxide, propylene oxide, butylene oxide, etc.) having from two to about 20 carbon atoms, or from two to about four. Examples of polyhydric amines include tri-(hydroxypropyl)amine, tris-(hydroxymethyl)amino methane, 2-amino-2-methyl-1,3-propanediol, N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine, and N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine, preferably tris(hydroxymethyl)amino-methane (THAM). Other heterocyclic amines can also include aromatic polycyclic amines. Examples of aromatic polycyclic amines include tolytriazole and benzotriazole.

The amines mentioned above can be used as a neutralization agent for the alkyl or aryl phosphoric acid, dialkyl or diaryl phosphoric acid, or their mixtures as well as an over-neutralization agent to obtain an overbased alkyl or aryl phosphate, or a dialkyl or diaryl phosphate, or their mixtures. The preferred amine phosphate is a dialkylphosphoric acid, first neutralized with a dialkyl amine, and then over-neutralized with a tolytriazole. More preferably, the dialkylphosphoric acid is a dihexylphosporic acid.

The other phosphates that could be used as ashless antiwear include triaryl phosphates, trialkyl phosphates, trialkylaryl phosphates, triarylalkyl phosphates and trialkenyl phosphates. As specific examples of these, referred to are triphenyl phosphate, tricresyl phosphate, benzyldiphenyl phosphate, ethyldiphenyl phosphate, tributyl phosphate, ethyldibutyl phosphate, cresyldiphenyl phosphate, dicresylphenyl phosphate, ethylphenyldiphenyl phosphate, diethylphenylphenyl phosphate, propylphenyldiphenyl phosphate, dipropylphenylphenyl phosphate, triethylphenyl phosphate, tripropylphenyl phosphate, butylphenyldiphenyl phosphate, dibutylphenylphenyl phosphate, tributylphenyl phosphate, trihexyl phosphate, tri(2-ethylhexyl) phosphate, tridecyl phosphate, trilauryl phosphate, trimyristyl phosphate, tripalmityl phosphate, tristearyl phosphate, and trioleyl phosphate.

In alternative embodiments, the antiwear additive can be ash-forming and thus can include at least one metal alkyldithiophosphate, particularly a metal dialkyldithiophosphate. Examples of suitable metal dialkyldithiophosphates include a molybdenum dialkyldithiophosphate (MoDTP), a primary zinc dialkyldithiophosphate (ZDDP) (derived from a primary alcohol), a secondary ZDDP (derived from a secondary alcohol), and combinations thereof. Such metal dialkyldithiophosphates can be derived from primary alcohols, secondary alcohols, or mixtures thereof. Examples of alcohols suitable for making ZDDP include 2-propanol, butanol, secondary butanol, pentanols, and hexanols such as 4-methyl-2-pentanol, n-hexanol, n-octanol, 2-ethyl hexanol, alkylated phenols, and the like. Mixtures of secondary alcohols or of a primary alcohol and a secondary alcohol are preferred. Alkyl aryl groups can also be used.

Preferred zinc dithiophosphates are secondary zinc dithiophosphates. Examples of suitable secondary zinc dithiophosphates include: Lubrizol 1389, and Lubrizol 1371, which are commercially available from The Lubrizol Corporation; OLOA 262, which is commercially available from Chevron Oronite; and HITEC 7169, which is commercially available from Afton Chemical. Mixtures of primary and secondary zinc dithiophosphates are also preferred. One preferred primary ZDDPs is Lubrizol 1095, which is commercially available from The Lubrizol Corporation.

The amount of ZDDP used in the lubricant composition can range from about 0 mass % to about 1.20 mass %, preferably from about 0.60 mass % to about 1.00 mass %, and more preferably from about 0.80 mass % to about 1.00 mass %, based on the total mass of the lubricant composition. Preferably, the ZDDP is a mixture of primary and secondary ZDDP at a ratio of approximately 1:4 and is present in an amount of from about 0.80 mass % to about 1.00 mass %, based on the total mass of the lubricant composition.

Illustrative molybdenum-containing compounds useful in the lubricant composition include oil-soluble decomposable organo molybdenum compounds such as Molyvan™ 855, which is commercially available from Vanderbilt Chemicals, LLC. Molyvvan™ 855 is an oil soluble secondary diarylamine defined as being substantially free of active phosphorus and active sulfur and is described in Vanderbilt's Material Data and Safety Sheet as an organomolybdenum compound having a density of 1.04 and a viscosity at 100° C. of 47.12 cSt. In general, organo molybdenum compounds are preferred because of their superior solubility and effectiveness.

Examples of other suitable organo molybdenum compounds include Molyvan™ L and Molyvan™ A, which are also commercially available from Vanderbilt Chemicals, LLC. Molvvan™ L is a sulfonated oxymolybdenum dialkyldithiophosphate described in U.S. Pat. No. 5,055,174, which is incorporated herein by reference. Molyvan™ A contains about 28.8 mass % Mo, 31.6 mass % C, 5.4 mass % H, and 25.9 mass % S. Also useful are Molyvan™ 822, Molyvan™ 856, and Molyvan™ 807.

Also useful is Sakura Lube™ 500, which is a more soluble Mo dithiocarbamate-containing lubricant additive commercially available from Asahi Denki Corporation. Sakura Lube™ 500 contains about 20.2 mass % Mo, 43.8 mass % C, 7.4 mass % H, and 22.4 mass % S. Sakura Lube™ 300, i.e., a low sulfur molybdenum dithiophosphate having a molybdenum to sulfur ratio of 1:1.07, is a preferred molybdenum-containing compound also available from Asahi Denki Corporation.

Another useful molybdenum-containing compound is Molyvan™ 807, which is also commercially available from Vanderbilt Chemicals, LLC. Molvvan™ is a mixture of about 50 mass % molybdenum ditridecyldithyocarbonate and about 50 mass % of an aromatic oil having a specific gravity of about 38.4 SUS and containing about 4.6 mass % molybdenum.

Other suitable organo molybdenum compounds include Mo(Co)₆, molybdenum octoate, MoO(C₇H₁₅CO₂)₂ which contains about 8 mass % Mo and is commercially available from Aldrich Chemical Company, and molybdenum naphthenethioctoate which is commercially available from Shephard Chemical Company.

It is recognized that the lubricant composition can include one or more inorganic molybdenum compounds such as molybdenum sulfide and molybdenum oxide; however such inorganice compounds are less preferred than the organo molybdenum compounds like Molyvan™ 855, Molyvan™ 822, Molyvan™ 856, and Molyvan™ 807.

Examples of other suitable molybdenum-containing compounds can be found in U.S. Patent Application Publication No. 2003/0119682, which is incorporated herein by reference.

The amount of molybdenum-containing compound used in the lubricant compositions can range from about 0 mass % to about 3.00 mass %, more preferably from about 0.10 mass % to about 1.50 mass %, and more preferably from about 0.10 mass % to about 1.20 mass %, based on the total mass of the lubricant composition. When describing in terms of ppm by mass, the the preferred concentration of the molybdenum element is from about 100 to about 2,000 ppm by mass, more preferably from about 500 to about 1500 ppm by mass, even more preferably from about 700 to about 1200 ppm by mass, and most preferably from about 900 to about 1,000 ppm by mass of molybdenum.

Friction Modifier

The lubricant composition can further include a friction modifier to reduce friction between moving parts. A friction modifier can be or can include any material that can alter the coefficient of friction of a surface lubricated by a lubricant or fluid containing such material. Friction modifiers, also known as friction reducers, lubricity agents or oiliness agents, etc. can be used in combination with the oil base stock or the lubricant composition disclosed herein to modify the coefficient of friction of a lubricated surface. Friction modifiers that lower the coefficient of friction are particularly advantageous. The lubricant composition can exhibit desired properties, e.g., wear control, in the presence or absence of a friction modifier.

Illustrative friction modifiers useful in the lubricant composition include the molybdenum compounds mentioned above as well as alkoxylated fatty acid esters, alkanolamides, polyol fatty acid esters, borated glycerol fatty acid esters, fatty alcohol ethers, and mixtures thereof.

Illustrative alkoxylated fatty acid esters include polyoxyethylene stearate, fatty acid polyglycol ester, and the like. These can include polyoxypropylene stearate, polyoxybutylene stearate, polyoxyethylene isosterate, polyoxypropylene isostearate, polyoxyethylene palmitate, and the like.

Illustrative alkanolamides include lauric acid diethylalkanolamide, palmic acid diethylalkanolamide, and the like. These can include oleic acid diethyalkanolamide, stearic acid diethylalkanolamide, oleic acid diethylalkanolamide, polyethoxylated hydrocarbylamides, polypropoxylated hydrocarbylamides, and the like.

Illustrative polyol fatty acid esters include glycerol mono-oleate, saturated mono-, di, and tri-glyceride esters, glycerol mono-stearate, and the like. These can include polyol esters, hydroxyl-containing polyol esters, and the like.

Illustrative borated glycerol fatty acid esters include borated glycerol mono-oleate, borated saturated mono-, di-, and tri-glyceride esters, borated glycerol mono-sterate, and the like. In addition to glycerol polyols, these can include trimethylolpropane, pentaerythritol, sorbitan, and the like. These esters can be polyol monocarboxylate esters, polyol dicarboxylate esters, and on occasion polyoltricarboxylate esters. Preferred can be the glycerol mono-oleates, glycerol dioleates, glycerol trioleates, glycerol monostearates, glycerol distearates, and glycerol tristearates and the corresponding glycerol monopalmitates, glycerol dipalmitates, and glycerol tripalmitates, and the respective isostearates, linoleates, and the like. On occasion the glycerol esters can be preferred as well as mixtures containing any of these. Ethoxylated, propoxylated, butoxylated fatty acid esters of polyols, especially using glycerol as underlying polyol can be preferred.

Illustrative fatty alcohol ethers include stearyl ether, myristyl ether, and the like. Alcohols, including those that have carbon numbers from C₃ to C₅₀, can be ethoxylated, propoxylated, or butoxylated to form the corresponding fatty alkyl ethers. The underlying alcohol portion can preferably be stearyl, myristyl, C₁₁-C₁₃ hydrocarbon, oleyl, isosteryl, and the like.

The concentration of friction modifier present in the lubricant composition can range from about 0.01 mass % to about 5.00 mass %, preferably from about 0.10 mass % to about 2.50 mass %, more preferably from about 0.10 mass % to about 1.50 mass %, or most preferably from about 0.10 mass % to about 1.20 mass %. Concentrations of molybdenum-containing materials are often described in terms of Mo metal concentration. Advantageous concentrations of Mo can range from 50 to 1500 ppm or more, and often with a preferred range of from 100 to 1200 ppm. Friction modifiers of all types can be used alone or in mixtures with the materials disclosed herein. Often mixtures of two or more friction modifiers, or mixtures of friction modifier(s) with alternate surface active material(s), are also desirable.

Ashless Detergent

The lubricant composition can include an ashless detergent to maintain engine cleanliness and inhibit contaminants from being deposited on engine parts. The ashless detergent can be or can include a nonionic detergent such as polyoxyethylene, polyoxypropylene, and polyoxybutylene alkyl ethers. For reference, see “Nonionic Surfactants: Physical Chemistry” Martin J. Schick, CRC Press; 2^(nd) edition (Mar. 27, 1987). These ashless detergents are less common in engine lubricant formulations but offer a number of advantages such as improved solubility in monoester based oils.

The most preferred detergents are ashless nonionic detergents with a Hydrophilic-Lipophilic Balance (HLB) value of 10 or below. Such detergents are commercially available from, e.g., Croda Inc. under the tradename Alarmol™ PS11E and Alarmol™ PS15E and from the Dow Chemical Co. under the tradename Ecosurf™ EH-3, Tergitol™ 15-S-3, Tergitol™ L-61, Tergitol™ L-62, Tergitol™ NP-4, Tergitol™ NP-6, Tergitol™ NP-7, Tergitol™ NP-8, Tergitol™ NP-9, Triton™ X-15, and Triton™ X-35.

The detergent concentrations disclosed herein are given on an “as delivered” basis. Typically, the active detergent is delivered with a process oil. The “as delivered” detergent can include from about 0 mass % to about 2.00 mass %, more preferably from about 0.80 to about 1.50 mass %, of active detergent in the “as delivered” detergent product.

Metal-Containing Detergents

Metal-containing detergents are commonly used in lubricating compositions. A typical detergent is an anionic material that contains a long chain hydrophobic portion of the molecule and a smaller anionic or oleophobic hydrophilic portion of the molecule. The anionic portion of the detergent is typically derived from an organic acid such as a sulfur acid, carboxylic acid, phosphorous acid, phenol, or mixtures thereof. The counterion is typically an alkaline earth or alkali metal.

Salts that contain a substantially stochiometric amount of the metal are described as neutral salts and have a total base number (TBN, as measured by ASTM D2896) of from 0 to 80. Many metal-containing detergents are overbased, containing large amounts of a metal base that is achieved by reacting an excess of a metal compound (e.g., a metal hydroxide or oxide) with an acidic gas (such as carbon dioxide). Useful detergents can be neutral, mildly overbased, or highly overbased.

It is desirable for at least some detergent to be overbased. Overbased detergents help neutralize acidic impurities produced by the combustion process and become entrapped in the oil. Typically, the overbased material has a ratio of metallic ion to anionic portion of the detergent of about 1.05:1 to 50:1 on an equivalent basis. More preferably, the ratio is from about 4:1 to about 25:1. The resulting detergent is an overbased detergent that will typically have a TBN of about 150 or higher, often about 250 to 450 or more. Preferably, the overbasing cation is sodium, calcium, or magnesium. A mixture of detergents of differing TBN can be used in the present invention.

Preferred detergents include the alkali or alkaline earth metal salts of sulfonates, phenates, carboxylates, phosphates, and salicylates.

Sulfonates can be prepared from sulfonic acids that are typically obtained by sulfonation of alkyl substituted aromatic hydrocarbons. Hydrocarbon examples include those obtained by alkylating benzene, toluene, xylene, naphthalene, biphenyl and their halogenated derivatives (e.g., chlorobenzene, chlorotoluene, and chloronaphthalene). The alkylating agents typically have about 3 to 70 carbon atoms. The alkaryl sulfonates typically contain about 9 to about 80 carbon or more carbon atoms, more typically from about 16 to 60 carbon atoms.

Klamann in Lubricants and Related Products, op. cit., discloses a number of overbased metal salts of various sulfonic acids which are useful as detergents and dispersants in lubricants. The book entitled “Lubricant Additives”, C. V. Smallheer and R. K. Smith, published by the Lezius-Hiles Co. of Cleveland, Ohio (1967), similarly discloses a number of overbased sulfonates that are useful as dispersants/detergents.

Alkaline earth phenates can be made by reacting alkaline earth metal hydroxide or oxide (e.g., CaO, Ca(OH)₂, BaO, Ba(OH)₂, MgO, Mg(OH)₂) with an alkyl phenol or sulfurized alkylphenol. Useful alkyl groups include straight chain or branched C₁-C₃₀ alkyl groups, preferably, C₄-C₂₀. Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It should be noted that starting alkylphenols can contain more than one alkyl substituent that are each independently straight chain or branched. When a non-sulfurized alkylphenol is used, the sulfurized product can be obtained by methods commonly known in the art. These methods include heating a mixture of alkylphenol and sulfurizing agent (including elemental sulfur, sulfur halides such as sulfur dichloride, and the like) and then reacting the sulfurized phenol with an alkaline earth metal base.

Metal salts of carboxylic acids are also useful as detergents. These carboxylic acid detergents can be prepared by reacting a basic metal compound with at least one carboxylic acid and removing free water from the reaction product. These compounds can be overbased to produce the desired TBN level. Detergents made from salicylic acid are one preferred class of detergents derived from carboxylic acids. Useful salicylates include long chain alkyl salicylates. One useful family of compositions has the following formula:

where R is a hydrogen atom or an alkyl group having 1 to about 30 carbon atoms, n is an integer from 1 to 4, and M is an alkaline earth metal. Preferred R groups are alkyl chains of at least C₁₁, preferably C₁₃ or greater. R may be optionally substituted with substituents that do not interfere with the detergent's function. M is preferably, calcium, magnesium, or barium. More preferably, M is calcium.

Hydrocarbyl-substituted salicylic acids can be prepared from phenols by the Kolbe reaction. See U.S. Pat. No. 3,595,791 for additional information on synthesis of these compounds. The metal salts of the hydrocarbyl-substituted salicylic acids can be prepared by double decomposition of a metal salt in a polar solvent such as water or alcohol.

Detergents can be classified as simple detergents or what is known as hybrid or complex detergents. The latter detergents can provide the properties of two detergents without the need to blend separate materials. See, for example, U.S. Pat. No. 6,034,039 for information regarding these detergents

Preferred detergents include calcium phenates, calcium sulfonates, calcium salicylates, magnesium phenates, magnesium sulfonates, magnesium salicylates, and other related components (including borated detergents). The total detergent concentration in the lubricant composition can range from about 0.01 mass % to about 6.00 mass %, preferably from about 0.10 mass % to about 4.00 mass %.

Dispersants

The lubricant composition can also include at least one dispersant. During engine operation, oil-insoluble oxidation byproducts can be produced. Dispersants can help keep these byproducts in solution, thus diminishing their deposition on metal surfaces. Dispersants used the lubricating composition can be ashless or ash-forming in nature. Preferably, the dispersant is ashless, meaning that it is an organic material that forms substantially no ash upon combustion. For example, non-metal-containing or borated metal-free dispersants are considered ashless. In contrast, metal-containing detergents discussed above form ash upon combustion.

Such dispersants can be present in the lubricant composition in an amount of about 1.00 mass % to about 6.00 mass %, preferably from about 1.00 mass % to about 4.00 mass %, based on a total mass of the lubricant composition. The hydrocarbon numbers of the dispersant atoms can range from C60 to C1000, or from C70 to C300, or from C70 to C200. These dispersants can contain both neutral and basic nitrogen or mixtures of both. The dispersants can be end-capped by borates and/or cyclic carbonates.

Suitable dispersants can contain a polar group attached to a relatively high molecular weight hydrocarbon chain. The polar group typically contains at least one element of nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

A particularly useful class of dispersants are the alkenylsuccinic derivatives, typically produced by the reaction of a long chain hydrocarbyl substituted succinic compound, usually a hydrocarbyl substituted succinic anhydride, with a polyhydroxy or polyamino compound. The long chain hydrocarbyl group constituting the oleophilic portion of the molecule which confers solubility in the oil is normally a polyisobutylene group. Many examples of this type of dispersant are well known commercially and in the literature. See, for example, U.S. Pat. Nos. 3,172,892; 3,215,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511; 3,787,374; and 4,234,435. Other types of dispersant are described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; and 5,705,458. A further description of dispersants can be found, for example, in European Patent Application No. 471 071.

Hydrocarbyl-substituted succinic acid and hydrocarbyl-substituted succinic anhydride derivatives also can be used as dispersants. In particular, succinimide, succinate esters, or succinate ester amides prepared by the reaction of a hydrocarbon-substituted succinic acid compound, preferably having at least 50 carbon atoms in the hydrocarbon substituent, with at least one equivalent of an alkylene amine, are particularly useful. On occasion, having a hydrocarbon substituent having 20 to 50 carbon atoms can be useful.

Succinimides can be formed by the condensation reaction between hydrocarbyl substituted succinic anhydrides and amines. Molar ratios can vary depending on the polyamine. For example, the molar ratio of hydrocarbyl substituted succinic anhydride to TEPA can vary from 1:1 to 5:1. Representative examples are shown in U.S. Pat. Nos. 3,087,936; 3,172,892; 3,219,666; 3,272,746; 3,322,670; 3,652,616; and 3,948,800; and in Canada Patent No. 1,094,044.

Succinate esters can be formed by the condensation reaction between hydrocarbyl substituted succinic anhydrides and alcohols or polyols. Molar ratios can vary depending on the alcohol or polyol used. For example, the condensation product of a hydrocarbyl substituted succinic anhydride and pentaerythritol is a useful dispersant.

Succinate ester amides can be formed by a condensation reaction between hydrocarbyl substituted succinic anhydrides and alkanol amines. Suitable alkanol amines include ethoxylated polyalkylpolyamines, propoxylated polyalkylpolyamines, and polyalkenylpolyamines such as polyethylene polyamines. One example is propoxylated hexamethylenediamine. Representative examples are shown in U.S. Pat. No. 4,426,305.

The molecular weight of the hydrocarbyl substituted succinic anhydrides typically ranges between 800 and 2,500 or more. The above products can be post-reacted with various reagents such as sulfur, oxygen, formaldehyde, and carboxylic acids such as oleic acid. The above products can also be post reacted with boron compounds such as boric acid, borate esters, and highly borated dispersants, to form borated dispersants generally having from 0.1 to 5.0 moles of boron per mole of dispersant reaction product.

Mannich based dispersants can also be used and are made from the reaction of alkylphenols, formaldehyde, and amines. See U.S. Pat. No. 4,767,551, which is incorporated herein by reference. Process aids and catalysts, such as oleic acid and sulfonic acids, can also be part of the reaction mixture. Molecular weights of the alkylphenols can range from 800 to 2,500. Representative examples are shown in U.S. Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039.

Typical high molecular weight aliphatic acid modified Mannich condensation products can be prepared from high molecular weight alkyl-substituted hydroxyaromatics or HNR₂ group-containing reactants.

Hydrocarbyl substituted amine ashless dispersant additives are well known to those skilled in the art. See, for example, U.S. Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433; 3,822,209; and 5,084,197.

Preferred dispersants include borated and non-borated succinimides, including those derivatives from mono-succinimides, bis-succinimides, and/or mixtures of mono- and bis-succinimides, wherein the hydrocarbyl succinimide is derived from a hydrocarbylene group such as polyisobutylene having a Mn of from 500 to 5,000, or from 1,000 to 3,000, or from 1,000 to 2,000, or a mixture of such hydrocarbylene groups, often with high terminal vinylic groups. Other preferred dispersants include succinic acid-esters and amides, alkylphenol-polyamine-coupled Mannich adducts, their capped derivatives, and other related components.

Polymethacrylate or polyacrylate derivatives are another class of dispersants. These dispersants are typically prepared by reacting a nitrogen containing monomer and a methacrylic or acrylic acid ester containing 5 to 25 carbon atoms in the ester group. Representative examples are shown in U.S. Pat. Nos. 2,100,993 and 6,323,164. Polymethacrylate and polyacrylate dispersants are normally used as multifunctional viscosity index improvers. The lower molecular weight versions can be used as lubricant dispersants or fuel detergents.

The use of polymethacrylate or polyacrylate dispersants are preferred in polar esters of a non-aromatic dicarboxylic acid, preferably adipate esters, since many other conventional dispersants are less soluble. The preferred dispersants for polyol esters include polymethacrylate and polyacrylate dispersants.

Viscosity Index Improver

One or more viscosity index improvers (also known as VI improvers, viscosity modifiers, and viscosity improvers) can be included in the lubricant composition. Viscosity index improvers can serve to provide lubricants with high and low temperature operability. These additives impart shear stability at elevated temperatures and acceptable viscosity at low temperatures. The viscosity index improver can be present the lubricant composition in an amount of from about 0.50 mass % to about 2.00 mass %, preferably from about 0.60 mass % to about 1.50 mass %, more preferably from about 0.60 mass % to about 1.20 mass %, based on the total mass of the lubricant composition.

Suitable viscosity index improvers include high molecular weight hydrocarbons, polyesters, and viscosity index improver dispersants that function as both a viscosity index improver and a dispersant. Typical molecular weights of these polymers are between about 10,000 to 1,500,000, more typically about 20,000 to about 1,200,000, and even more typically about 50,000 to about 1,000,000. The typical molecular weight for polymethacrylate or polyacrylate viscosity index improvers is less than about 50,000.

Examples of suitable viscosity index improvers are linear or star-shaped polymers and copolymers of methacrylate, butadiene, olefins, or alkylated styrenes. Polyisobutylene is a commonly used viscosity index improver. Another suitable viscosity index improver is polymethacrylate (e.g., copolymers of various chain length alkyl methacrylates), some formulations of which also serve as pour point depressants. Other suitable viscosity index improvers include copolymers of ethylene and propylene, hydrogenated block copolymers of styrene and isoprene, and polyacrylates (copolymers of various chain length acrylates, for example). Specific examples include styrene-isoprene or styrene-butadiene based polymers having a molecular weight of about 50,000 to 200,000.

Suitable olefin copolymers are commercially available from: Chevron Oronite Company LLC under the tradename PARATONE® (such as PARATONE® 8921 and PARATONE® 8941); Afton Chemical Corporation under the tradename HiTEC® (such as HiTEC® 5850B; and The Lubrizol Corporation under the tradename Lubrizol® 7067C. Hydrogenated polyisoprene star polymers are commercially available from Infineum International Limited, e.g., under the tradename SV200 and SV600. Hydrogenated diene-styrene block copolymers are commercially available from Infineum International Limited, e.g., under the tradenames SV40 and SV50.

As used herein, the viscosity index improver concentrations are given on an “as delivered” basis. Typically, the active polymer is delivered with a diluent oil. The “as delivered” viscosity index improver typically contains from about 20 to about 75 mass % of an active polymer for polymethacrylate or polyacrylate polymers, or from about 8 to about 20 mass % of an active polymer for olefin copolymers, hydrogenated polyisoprene star polymers, or hydrogenated diene-styrene block copolymers, in the “as delivered” polymer concentrate.

Antioxidant

Also, the lubricant composition can include an antioxidant to retard the oxidative degradation of the oil base stock. Such degradation could result in deposits on metal surfaces, the presence of sludge, or a viscosity increase in the lubricant composition. The concentration of the antioxidant in the lubricant composition can range from about 1.50 mass % to about 11.25 mass %. The antioxidant can be or can include a phenolic antioxidant, an aminic antioxidant, a polymeric aminic antioxidant, or combinations thereof.

A phenolic antioxidant is typically a hindered phenolic which contains a sterically hindered hydroxyl group, including those derivatives of dihydroxy aryl compounds in which the hydroxyl groups are in the o- or p-position to each other. Suitable hindered phenols can include hindered phenols substituted with C₆₊ alkyl groups and the alkylene coupled derivatives of those hindered phenols such as 2-t-butyl-4-heptyl phenol, 2-t-butyl-4-octyl phenol, 2-t-butyl-4-dodecyl phenol, 2,6-di-t-butyl-4-heptyl phenol, 2,6-di-t-butyl-4-dodecyl phenol, 2-methyl-6-t-butyl-4-heptyl phenol, and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful hindered mono-phenolic antioxidants can include, e.g., hindered 2,6-di-alkyl-phenolic proprionic ester derivatives. Bis-phenolic antioxidants can also be advantageously used in combination with the hindered phenolic antioxidants. Suitable ortho-coupled phenols can include: 2,2′-bis(4-heptyl-6-t-butyl-phenol); 2,2′-bis(4-octyl-6-t-butyl-phenol); and 2,2′-bis(4-dodecyl-6-t-butyl-phenol). Suitable para-coupled bisphenols can include: 4,4′-bis(2,6-di-t-butyl phenol); and 4,4′-methylene-bis(2,6-di-t-butyl phenol).

An aminic antioxidant is typically an aromatic amine antioxidant. Suitable amine antioxidants can include alkylated and non-alkylated aromatic amines such as aromatic monoamines of the formula R⁸R⁹R¹⁰N, where R⁸ is an aliphatic, aromatic or substituted aromatic group, R⁹ is an aromatic or a substituted aromatic group, and R¹⁰ is H, alkyl, aryl or R¹¹S(O)_(x)R¹², where R¹¹ is an alkylene, alkenylene, or aralkylene group, R¹² is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1 or 2. The aliphatic group R⁸ can include from 1 to 20 carbon atoms and preferably include from 6 to 12 carbon atoms. Preferably, both R⁸ and R⁹ are aromatic or substituted aromatic groups, where the aromatic group can be a fused ring aromatic group such as naphthyl.

Suitable aromatic amine antioxidants can have alkyl substituent groups of at least 6 carbon atoms. Examples of aliphatic groups can include hexyl, heptyl, octyl, nonyl, and decyl. Typically, the aliphatic groups do not contain more than 14 carbon atoms. The general types of amine antioxidants useful in the lubricant composition disclosed herein include diphenylamines, phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenyl phenylene diamines. Mixtures of two or more aromatic amines can be used. Particular examples of suitable aromatic amine antioxidants include: p,p′-dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine; phenyl-alpha-naphthylamine; and p-octylphenyl-alpha-naphthylamine. Polymeric aminic antioxidants derived from these diphenylamines, phenyl naphthylamines, and their mixtures can also be used. The polymeric aminic antioxidants can be available in a concentrate form with active polymeric amines in the 10 to 40 mass %. Such polymeric aminic antioxidant concentrates are commercially available from, e.g., Nyco S.A. under the tradename Nycoperf AO 337.

Other suitable aminic antioxidants include polymeric or oligomeric amines which are the polymerization reaction products of one or more substituted or hydrocarbyl-substituted diphenyl amines, one or more unsubstituted or hydrocarbyl-substituted phenyl naphthyl amines, or both one or more of unsubstituted or hydrocarbyl-substituted diphenylamine with one or more unsubstituted or hydrocarbyl-substituted phenyl naphthylamine. A representative schematic is presented below:

wherein (a) and (b) each range from zero to 10, preferably zero to 5, more preferably zero to 3, most preferably 1 to 3, provided (a)+(b) is at least 2, for example:

where R² is a styrene or C₁ to C₃₀ alkyl, R³ is a styrene or C₁ to C₃₀ alkyl, R⁴ is a styrene or C₁ to C₃₀ alkyl, preferably R₂ is a C₁ to C₃₀ alkyl, R₃ is a C₁ to C₃₀ alkyl, R₄ is a C₁ to C₃₀ alkyl, more preferably R₂ is a C₄ to C₁₀ alkyl, R₃ is a C₄ to C₁₀ alkyl and R₄ is a C₄ to C₁₀ alkyl, p, q and y individually range from 0 to up to the valence of the aryl group to which the respective R group(s) are attached, preferably at least one of p, q and y range from 1 to up to the valence of the aryl group to which the respective R group(s) are attached, more preferably p, q and y each individually range from at least 1 to up to the valence of the aryl group to which the respective R groups are attached. Other more extensive oligomers are within the scope of this disclosure, but materials of formulae A, B, C and D are preferred. Examples can also be found in U.S. Pat. No. 8,492,321.

Other Additives

The lubricant composition can additionally include other lubricant performance additives known in the art such as corrosion inhibitors, rust inhibitors, metal deactivators, extreme pressure additives, anti-seizure agents, wax modifiers, fluid-loss additives, seal compatibility agents, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, and others. For a review of many commonly used additives, see Klamann in Lubricants and Related Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0. Reference is also made to “Lubricant Additives” by M. W. Ranney, published by Noyes Data Corporation of Parkridge, N.J. (1973); see also U.S. Pat. No. 7,704,930, which is incorporated by reference herein in its entirety. These additives are commonly delivered with varying amounts of diluent oil that may range from 5 to 50 mass %. When lubricating oil compositions include one or more of the foregoing additives, the additive(s) can be blended into the composition in an amount sufficient for it to perform its intended function.

EXAMPLES

The foregoing discussion can be further described with reference to the following non-limiting examples.

Three lubricant formulations (Examples (Ex.) 1-3) were made that contained monoesters in the base oil. The formulation of Ex.1 contained 2-octyldecylpelargonate and 2-ethylhexyllaurate as the monoesters. The formulation of Ex.1 also included ashless, sulfur-free, and low-phosphorus-containing additives such as an amine phosphate antiwear additive and an organic friction modifier commercially available from Croda Lubricants under the tradename Perfad™ 3336. The formulations of Ex.2-3 contained 2-ethylhexyllaurate and 2-ethylhexylpalmitate as the monoesters in the base oil, an organic friction modifier, and multiple metal-containing antiwear additives, i.e., a primary ZDDP, a secondary ZDDP, and MoDTP. The formulation of Ex.2 also included a small portion of polyalphaolefin (PAO) in the base oil whereas the formulation of Ex.3 included a large portion of PAO in the base oil. The PAO used in these examples is commercially available from ExxonMobil under the tradename SpectraSyn™ 6.

A comparative lubricant formulation (Comparative Example (C.Ex.) 1) was also prepared that contained only PAO as the base oil and no monoester. The PAO used in C.Ex.1 is commercially available from ExxonMobil under the tradename SpectraSyn™ 6.

The formulation of C.Ex.1 further included an organic friction modifier and a secondary ZDDP that had lower volatility than the secondary ZDDP included in the formulations of Ex.2-3.

The specific mass % of each component used in the formulations of Ex.1-3 and C.Ex.1 are provided in Table 1 below, where all mass percentages are based on the total mass of the lubricant formulation (less any diluent).

Each formulation was made by adding each component of the formulation to a beaker heated to a temperature of 70° C. to 85° C., followed by blending the components together with a stirrer.

TABLE 1 Formulations and Properties of Comparative Example 1 and Examples 1-3 C. Ex. 1 Ex. 1 Ex. 2 Ex. 3 PAO, mass % 79.94 14.10 54.10 2-Octyldecylpelargonate 74.28 (monoester), mass % 2-Ethylhexyllaurate 10.80 59.52 19.52 (monoester), mass % 2-Ethylhexylpalmitate 13.47 13.47 (monoester), mass % Organic friction modifier, 0.50 0.50 2.00 2.00 mass % Secondary zinc dialkyldithio- 1.30 phosphate 1 (antiwear additive), mass % Secondary zinc dialkyldithio- 0.75 0.75 phosphate 2 (antiwear additive), mass % Primary zinc dialkyldithio- 0.22 0.22 phosphate (antiwear additive), mass % Amine phosphate (antiwear 0.25 additive), mass % Molybdenum dialkyldithio- 1.16 1.16 phosphate (antiwear additive), mass % Other additives 1, mass % 18.26 Other additives 2, mass % 14.17 Other additives 3, mass % 8.78 8.78

The foregoing lubricant formulations were tested to determine various properties thereof, which are recorded in Table 2 below. Table 2 also provides the test method that was employed to determine each property. First, the kinematic viscosities of C.Ex.1 and Ex.1-3 were measured at both 40° C. and 100° C. In addition, the High Temperature High Shear (HTHS) viscosity at 150° C. was determined for each formulation. The HTHS viscosity helps predict the behavior of an engine oil under more severe operating conditions. The Viscosity Index of each formulation was also calculated. As illustrated in Table 2, the kinematic viscosity values at 40° C. were surprisingly lower for Ex.1-3 than for C.Ex.1, indicating that the inventive lubricant formulations can have better energy efficiency than conventional lubricant formulations at a lower temperature.

All of the formulations of C.Ex.1 and Ex.1-3 were subjected to a test procedure known as the “Friction Coefficient Test” to determine the average friction coefficient of each formulation. The Friction Coefficient Test was performed using a Mini-Traction Machine (MTM) manufactured by PCS Instruments of London, United Kingdom. The MTM was operated using a 19.05 mm (¾ inch) diameter ball composed of AISI 52100 bearing steel and a 46 mm diameter disc composed of AISI 52100 bearing steel. The disc was held in a bath containing the test lubricant formulation to ensure that the contact area between the ball and the flat surface of the disc was fully immersed. The ball shaft was aligned with respect to the disc to prevent spin in the contact, and the slide to roll ratio (SRR) was controlled independently by driving both the ball and disc with separate motors. The SSR was set at 50%, the load was set at 1.00 GPa, and the temperature was set at 140° C. The speed of the MTM was varied from 0 to 300 mm/s. The Friction Coefficient Test was repeated four times. For the fourth run, twenty data points spaced apart based on a logarithmic scale were obtained between 0 to 100 mm/s. The average of these twenty data points for each formulation was reported in Table 2 below as the average friction coefficient.

As illustrated in FIG. 1 , the average friction coefficient was surprisingly lower for the formulations containing monoesters in the oil base stock (Ex.1-3) than for the formulation containing only PAO in the oil base stock (C.Ex.1). The average friction coefficient was unexpectedly lowest for the formulation containing both monoesters and a small amount of PAO in the oil base stock (Ex. 2).

All of the formulations of C.Ex.1 and Ex.1-3 were further subjected to a test procedure known as the “Traction Coefficient Test” to determine the traction coefficient of each formulation at different temperatures. The Traction Coefficient Test was performed using the same MTM as the Friction Coefficient Test. The MTM was operated using a 19.05 mm (¾ inch) diameter ball composed of AISI 52100 bearing steel and a 46 mm diameter disc composed of AISI 52100 bearing steel. The disc was held in a bath containing the test lubricant formulation to ensure that the contact area between the ball and flat surface of the disc was fully immersed. The ball shaft was aligned with respect to the disc to prevent spin in the contact, and the SRR was controlled independently by driving both the ball and disc with separate motors. Each formulation was tested at temperatures between 40° C. and 140° C. while varying the SRR between 0 and 100. The speed of the MTM was operated at 2 m/s, and the load varied between 0.75 GPa and 1.25 GPa for each test.

The traction coefficients at 140° C., 120° C., and 60° C. with a consistent load of 1.25 GPa, speed of 2.0 m/s, and SRR of 100% were recorded in Table 2. Surprisingly, the traction coefficients at 140° C. and 60° C. were lower for the formulations containing monoesters in the oil base stock (Ex.1-3) than for the formulation containing only PAO in the oil base stock (C.Ex.1). It was also surprising that the traction coefficients at 120° C. were lower for the formulations primarily containing monoesters in the oil base stock (Ex.1-2) than for the formulation containing only PAO in the oil base stock. The traction coefficient at 120° C. for the formulation containing both monoesters and a large amount of PAO in the oil base stock (Ex.3) was similar to that of the formulation containing only PAO in the oil base stock. FIG. 2 more clearly illustrates the continuous drop in traction coefficient from the formulation of C.Ex.1 to the formulation of Ex. 1 to the formulation of Ex. 2. The traction coefficients, like the friction coefficient, were unexpectedly lowest for the formulation containing both monoesters and a small amount of PAO in the oil base stock (Ex. 2).

The amount of metal (i.e., boron, calcium, magnesium, molybdenum, and zinc) and the amount of phosphorus present in each lubricant formulation was determined using ASTM D4951. Also, the amount of sulfur present in each formulation was also found using ASTM D6443. As depicted in Table 2, the concentrations of each metal component and phosphorus were found to be lower in the formulation of Ex. 1 than in the formulations of C.Ex.1, Ex.2, and Ex.3, with the exception that the magnesium mass % and the molybdenum mass % was the same for the formulations of C.Ex.1 and Ex.1. The concentration of each metal component in the formulation of Ex. 1 was less than 0.001, the sulfur content in the formulation of Ex. 1 was less than 0.0005, and the phosphorus content in the formulation of Ex. 1 was 0.009. These results indicate that the lubricant formulation of Ex. 1 was a sulfur-free, ashless, and low phosphorus-containing formulation.

TABLE 2 Properties of Comparative Example 1 and Examples 1-3 C. Ex. 1 Ex. 1 Ex. 2 Ex. 3 Kinematic Viscosity at 100° C., ASTM D445 7.82 6.78 6.70 9.69 Kinematic Viscosity at 40° C., ASTM D445 40.65 35.91 34.48 40.40 Viscosity Index (VI), Calculated 167 150 155 237 High Temperature High Shear Viscosity 2.6 2.3 2.4 2.2 (HTHS) at 150° C., ASTM D4683 Boron mass %, ASTM D4951 0.0300 <0.0010 0.0300 0.0244 Calcium mass %, ASTM D4591 0.168 <0.001 0.109 0.111 Magnesium mass %, ASTM D4951 <0.001 <0.001 0.074 0.076 Molybdenum mass %, ASTM D4591 <0.001 <0.001 0.108 0.106 Phosphorus mass %, ASTM D4591 0.113 0.009 0.127 0.126 Zinc mass %, ASTM D4591 0.126 <0.001 0.101 0.101 Sulfur mass %, ASTM D6443 0.2530 <0.0005 0.2884 Average Friction Coefficient at 140° C., 1.00 0.1207 0.0815 0.0443 0.0554 GPa, and 50% SRR Traction Coefficient at 140° C., 1.25 GPa, 0.0277 0.0206 0.0175 0.0225 100% SRR Traction Coefficient at 120° C., 1.25 GPa, 0.0244 0.0212 0.0171 0.0246 100% SRR Traction Coefficient at 60° C., 1.25 GPa, 0.0334 0.0284 0.0265 0.0315 100% SRR

LISTING OF EMBODIMENTS

This disclosure may further include any one or more of the following non-limiting embodiments:

1. A lubricant composition comprising: an oil base stock consisting essentially of at least one monoester, wherein a concentration of the at least one monoester is about 70.00 mass % to about 90.00 mass %; about 0.20 mass % to about 1.50 mass % of at least one antiwear additive; about 0.10 mass % to about 1.00 mass % of at least one friction modifier; about 1.00 mass % to about 4.00 mass % of at least one dispersant; less than about 0.5 mass % of phosphorus; less than about 0.1 mass % of sulfur; and less than about 0.5 mass % of ash, wherein all mass percentages are based on a total mass of the lubricant composition, wherein the lubricant composition has a first traction coefficient that is greater than about 0.010 and less than about 0.023, as measured by the Traction Coefficient Test at a temperature of about 140° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%, and wherein the lubricant composition has an average friction coefficient that is greater than about 0.01 and about less than about 0.10, as measured by the Friction Coefficient Test at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%.

2. The lubricant composition according to embodiment 1, further comprising less than about 0.01 mass % of the phosphorus, less than about 0.01 mass % of the sulfur, and less than about 0.1 mass % of the ash.

3. The lubricant composition according to embodiment 1 or 2, wherein the at least one monoester comprises 2-octyldecylpelargonate, 2-ethylhexylaurate, 2-ethylhexylpalmitate, or combinations thereof.

4. The lubricant composition according to any embodiment 1 to 3, wherein the at least one antiwear additive comprises amine phosphate.

5. The lubricant composition according to any embodiment 1 to 4, further comprising a second traction coefficient that is greater than about 0.010 and less than about 0.024, as measured by the Traction Coefficient Test at a temperature of about 120° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%

6. The lubricant composition according to any embodiment 1 to 5, further comprising a third traction coefficient that is greater than about 0.010 and less than about 0.032, as measured by the Traction Coefficient Test at a temperature of about 60° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.

7. A process of using the lubricant composition of according any embodiment 1 to 6, comprising: introducing the lubricant composition to at least one gearbox and at least one engine of a motorcycle.

8. A process for making a lubricant composition, comprising combining: an oil base stock consisting essentially of at least one monoester, wherein a concentration of the at least one monoester is from about 70.00 mass % to about 90.00 mass %; from about 0.20 mass % to about 1.50 mass % of at least one antiwear additive; from about 0.10 mass % to about 1.00 mass % of at least one friction modifier; from about 1.00 mass % to about 4.00 mass % of at least one dispersant; less than about 0.5 mass % of phosphorus; less than about 0.1 mass % of sulfur; and less than about 0.5 mass % of ash, wherein all mass percentages are based on a total mass of the lubricant composition.

9. A lubricant composition comprising: an oil base stock comprising at least one monoester and at least one polyalphaolefin, wherein a concentration of the at least one monoester is about 50.00 mass % to about 90.00 mass % and a concentration of the at least one polyalphaolefin is about 10.00 mass % to about 20.00 mass %; about 0.20 mass % to about 2.50 mass % of at least one antiwear additive; about 1.50 mass % to about 2.50 mass % of at least one friction modifier; and about 1.00 mass % to about 4.00 mass % of at least one dispersant, wherein all mass percentages are based on a total mass of the lubricant composition, wherein the lubricant composition has a first traction coefficient that is greater than about 0.010 and less than about 0.023, as measured by the Traction Coefficient Test at a temperature of about 140° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%, and wherein the lubricant composition has an average friction coefficient that is greater than about 0.01 and about less than about 0.10, as measured by the Friction Coefficient Test at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%.

10. The lubricant composition according to embodiment 9, wherein the at least one monoester comprises 2-octyldecylpelargonate, 2-ethylhexylaurate, 2-ethylhexylpalmitate, or combinations thereof.

11. The lubricant composition according to embodiment 9 or 10, wherein the at least one antiwear additive comprises a molybdenum dialkyldithiophosphate, a zinc dialkyldithiophosphate, or combinations thereof.

12. The lubricant composition according to embodiment 11, wherein a concentration of the molybdenum dialkyldithiophosphate in the lubricant composition is about 0.10 mass % to about 1.50 mass %, and wherein a concentration of the zinc dialkyldithiophosphate in the lubricant composition is about 0.60 mass % to about 1.00 mass %.

13. The lubricant composition according to any embodiment 1 to 12, further comprising a second traction coefficient that is greater than about 0.010 and less than about 0.024, as measured by the Traction Coefficient Test at a temperature of about 120° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.

14. The lubricant composition according to any embodiment 1 to 13, further comprising a third traction coefficient that is greater than about 0.010 and less than about 0.032, as measured by the Traction Coefficient Test at a temperature of about 60° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.

15. A process of using the lubricant composition according to any embodiment 1 to 14, comprising: introducing the lubricant composition to at least one gearbox and at least one engine of a motorcycle.

16. A process for making a lubricant composition, comprising combining: an oil base stock comprising at least one monoester and at least one polyalphaolefin, wherein a concentration of the at least one monoester is about 50.00 mass % to about 90.00 mass % and a concentration of the at least one polyalphaolefin is about 10.00 mass % to about 20.00 mass %; about 0.20 mass % to about 2.50 mass % of at least one antiwear additive; about 1.50 mass % to about 2.50 mass % of at least one friction modifier; and about 1.00 mass % to about 4.00 mass % of at least one dispersant, wherein all mass percentages are based on a total mass of the lubricant composition.

17. A lubricant composition comprising: an oil base stock comprising at least one monoester and at least one polyalphaolefin, wherein a concentration of the at least one monoester is about 15.00 mass % to about 30.00 mass % and a concentration of the at least one polyalphaolefin is about 30.00 mass % to about 55.00 mass %; about 0.20 mass % to about 2.50 mass % of at least one antiwear additive; about 1.50 mass % to about 2.50 mass % of at least one friction modifier; and about 1.00 mass % to about 4.00 mass % of at least one dispersant, wherein all mass percentages are based on a total mass of the lubricant composition, wherein the lubricant composition has a first traction coefficient that is greater than about 0.010 and less than about 0.023, as measured by the Traction Coefficient Test at a temperature of about 140° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%, and wherein the lubricant composition has an average friction coefficient that is greater than about 0.01 and about less than about 0.10, as measured by the Friction Coefficient Test at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%.

18. The lubricant composition according to claim 17, wherein the at least one monoester comprises 2-octyldecylpelargonate, 2-ethylhexylaurate, 2-ethylhexylpalmitate, or combinations thereof.

19. The lubricant composition according to claim 17 or 18, wherein the at least one antiwear additive comprises a molybdenum dialkyldithiophosphate, a zinc dialkyldithiophosphate, or combinations thereof.

20. The lubricant composition according to claim 19, wherein a concentration of the molybdenum dialkyldithiophosphate in the lubricant composition is about 0.10 mass % to about 1.50 mass %, and wherein a concentration of the zinc dialkyldithiophosphate in the lubricant composition is about 0.60 mass % to about 1.00 mass %.

21. The lubricant composition according to any embodiment 17 to 20, further comprising a second traction coefficient that is greater than about 0.010 and less than about 0.024, as measured by the Traction Coefficient Test at a temperature of about 120° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.

22. The lubricant composition according to any embodiment 17 to 21, further comprising a third traction coefficient that is greater than about 0.010 and less than about 0.032, as measured by the Traction Coefficient Test at a temperature of about 60° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.

23. A process of using the lubricant composition according to any embodiment 17 to 22, comprising: introducing the lubricant composition to at least one gearbox and at least one engine of a motorcycle.

24. A process for making a lubricant composition, comprising combining: an oil base stock comprising at least one monoester and at least one polyalphaolefin, wherein a concentration of the at least one monoester is about 15.00 mass % to about 30.00 mass % and a concentration of the at least one polyalphaolefin is about 30.00 mass % to about 55.00 mass %; about 0.20 mass % to about 2.50 mass % of at least one antiwear additive; about 1.50 mass % to about 2.50 mass % of at least one friction modifier; and about 1.00 mass % to about 4.00 mass % of at least one dispersant, wherein all mass percentages are based on a total mass of the lubricant composition.

Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and/or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

Various terms have been defined above. To the extent a term used in a claim is not defined above, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are fully incorporated by reference to the extent such disclosure is not inconsistent with this application and for all jurisdictions in which such incorporation is permitted.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1-24. (canceled)
 25. A lubricant composition comprising: an oil base stock consisting essentially of at least one monoester, wherein a concentration of the at least one monoester is about 70.00 mass % to about 90.00 mass %; about 0.20 mass % to about 1.50 mass % of at least one antiwear additive; about 0.10 mass % to about 1.00 mass % of at least one friction modifier; about 1.00 mass % to about 4.00 mass % of at least one dispersant; less than about 0.5 mass % of phosphorus; less than about 0.1 mass % of sulfur; and less than about 0.5 mass % of ash, wherein all mass percentages are based on a total mass of the lubricant composition, wherein the lubricant composition has a first traction coefficient that is greater than about 0.010 and less than about 0.023, as measured by the Traction Coefficient Test at a temperature of about 140° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%, and wherein the lubricant composition has an average friction coefficient that is greater than about 0.01 and about less than about 0.10, as measured by the Friction Coefficient Test at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%.
 26. The lubricant composition according to claim 25, further comprising less than about 0.01 mass % of the phosphorus, less than about 0.01 mass % of the sulfur, and less than about 0.1 mass % of the ash.
 27. The lubricant composition according to claim 1, wherein the at least one monoester comprises 2-octyldecylpelargonate, 2-ethylhexylaurate, 2-ethylhexylpalmitate, or combinations thereof.
 28. The lubricant composition according to claim 1, wherein the at least one antiwear additive comprises amine phosphate.
 29. The lubricant composition according to claim 1, further comprising a second traction coefficient that is greater than about 0.010 and less than about 0.024, as measured by the Traction Coefficient Test at a temperature of about 120° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.
 30. The lubricant composition according to claim 5, further comprising a third traction coefficient that is greater than about 0.010 and less than about 0.032, as measured by the Traction Coefficient Test at a temperature of about 60° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.
 31. A process of using the lubricant composition of according to claim 1, comprising: introducing the lubricant composition to at least one gearbox and at least one engine of a motorcycle.
 32. A lubricant composition comprising: an oil base stock comprising at least one monoester and at least one polyalphaolefin, wherein a concentration of the at least one monoester is about 50.00 mass % to about 90.00 mass % and a concentration of the at least one polyalphaolefin is about 10.00 mass % to about 20.00 mass %; about 0.20 mass % to about 2.50 mass % of at least one antiwear additive; about 1.50 mass % to about 2.50 mass % of at least one friction modifier; and about 1.00 mass % to about 4.00 mass % of at least one dispersant, wherein all mass percentages are based on a total mass of the lubricant composition, wherein the lubricant composition has a first traction coefficient that is greater than about 0.010 and less than about 0.023, as measured by the Traction Coefficient Test at a temperature of about 140° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%, and wherein the lubricant composition has an average friction coefficient that is greater than about 0.01 and about less than about 0.10, as measured by the Friction Coefficient Test at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%.
 33. The lubricant composition according to claim 32, wherein the at least one monoester comprises 2-octyldecylpelargonate, 2-ethylhexylaurate, 2-ethylhexylpalmitate, or combinations thereof.
 34. The lubricant composition according to claim 32, wherein the at least one antiwear additive comprises a molybdenum dialkyldithiophosphate, a zinc dialkyldithiophosphate, or combinations thereof.
 35. The lubricant composition according to claim 32, wherein a concentration of the molybdenum dialkyldithiophosphate in the lubricant composition is about 0.10 mass % to about 1.50 mass %, and wherein a concentration of the zinc dialkyldithiophosphate in the lubricant composition is about 0.60 mass % to about 1.00 mass %.
 36. The lubricant composition according to claim 32, further comprising a second traction coefficient that is greater than about 0.010 and less than about 0.024, as measured by the Traction Coefficient Test at a temperature of about 120° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.
 37. The process for making a lubricant composition according to claim 32, further comprising a third traction coefficient that is greater than about 0.010 and less than about 0.032, as measured by the Traction Coefficient Test at a temperature of about 60° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.
 38. A process for making a lubricant composition, comprising combining: an oil base stock consisting essentially of at least one monoester, wherein a concentration of the at least one monoester is from about 70.00 mass % to about 90.00 mass %; from about 0.20 mass % to about 1.50 mass % of at least one antiwear additive; from about 0.10 mass % to about 1.00 mass % of at least one friction modifier; from about 1.00 mass % to about 4.00 mass % of at least one dispersant; less than about 0.5 mass % of phosphorus; less than about 0.1 mass % of sulfur; and less than about 0.5 mass % of ash, wherein all mass percentages are based on a total mass of the lubricant composition wherein the lubricant composition has a first traction coefficient that is greater than about 0.010 and less than about 0.023, as measured by the Traction Coefficient Test at a temperature of about 140° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%, and wherein the lubricant composition has an average friction coefficient that is greater than about 0.01 and about less than about 0.10, as measured by the Friction Coefficient Test at a temperature of about 140° C., a pressure of about 1.00 GPa, and a slide to roll ratio of about 50%.
 39. The process for making a lubricant composition according to claim 8, further comprising a second traction coefficient that is greater than about 0.010 and less than about 0.024, as measured by the Traction Coefficient Test at a temperature of about 120° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%.
 40. The process for making a lubricant composition according to claim 8, further comprising a third traction coefficient that is greater than about 0.010 and less than about 0.032, as measured by the Traction Coefficient Test at a temperature of about 60° C., a pressure of about 1.25 GPa, and a slide to roll ratio of about 100%. 